title: Identification of the thiamin salvage enzyme thiazole kinase in Arabidopsis and maize.
abstract: The breakdown of thiamin (vitamin B1) and its phosphates releases a thiazole moiety, 4-methyl-5-(2-hydroxyethyl)thiazole (THZ), that microorganisms and plants are able to salvage for re-use in thiamin synthesis. The salvage process starts with the ATP-dependent phosphorylation of THZ, which in bacteria is mediated by ThiM. The Arabidopsis and maize genomes encode homologs of ThiM (At3g24030 and GRMZM2G094558, respectively). Plasmid-driven expression of either plant homolog restored the ability of THZ to rescue Escherichia coli thiM deletant strains, showing that the plant proteins have ThiM activity in vivo. Enzymatic assays with purified recombinant proteins confirmed the presence of THZ kinase activity. Furthermore, ablating the Arabidopsis At3g24030 gene in a thiazole synthesis mutant severely impaired rescue by THZ. Collectively, these results show that ThiM homologs are the main source of THZ kinase activity in plants and are consequently crucial for thiamin salvage.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Yazdani
authors.forename: Rémi
authors.initials: R
authors.lastname: Zallot
authors.forename: Meral
authors.initials: M
authors.lastname: Tunc-Ozdemir
authors.forename: Valérie
authors.initials: V
authors.lastname: de Crécy-Lagard
authors.forename: David K
authors.initials: DK
authors.lastname: Shintani
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hanson
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D009154:Mutation; D010770:Phosphotransferases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013831:Thiamine / Q000378:metabolism*; D013844:Thiazoles / Q000378:metabolism*; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; C437085:THI1 protein, Arabidopsis; D013844:Thiazoles; D010770:Phosphotransferases; C587553:At3g24030 protein, Arabidopsis; D017853:Phosphotransferases (Alcohol Group Acceptor); C051254:hydroxyethylthiazole kinase; D013831:Thiamine
keywords: Arabidopsis thaliana; Brassicaceae; Comparative genomics; Poaceae; Salvage; Thiamin; Thiazole; Zea mays